A major advantage of spread-spectrum communication systems is their ability to exploit the multipath structure of the received signal. A standard RAKE receiver estimates the time delay, attenuation, and angle of arrival of each path and uses a maximum-ratio combiner to recombine different path signals. Antenna array structures were proposed to mitigate the effects of multipath by separating the paths in both time and spatial domains. New techniques for estimating the spatio-temporal characteristics of the channel for coherent direct-sequence spread-spectrum systems are proposed. The simulation results present the performance of such a multichannel estimator.
{"title":"Spatio-temporal channel estimation techniques for multiple access spread spectrum systems with antenna arrays","authors":"B. Khalaj, A. Paulraj, T. Kailath","doi":"10.1109/ICC.1995.524456","DOIUrl":"https://doi.org/10.1109/ICC.1995.524456","url":null,"abstract":"A major advantage of spread-spectrum communication systems is their ability to exploit the multipath structure of the received signal. A standard RAKE receiver estimates the time delay, attenuation, and angle of arrival of each path and uses a maximum-ratio combiner to recombine different path signals. Antenna array structures were proposed to mitigate the effects of multipath by separating the paths in both time and spatial domains. New techniques for estimating the spatio-temporal characteristics of the channel for coherent direct-sequence spread-spectrum systems are proposed. The simulation results present the performance of such a multichannel estimator.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"3 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113937672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A problem has been identified with the handling of information tones by the full-rate GSM voice activity detector (VAD). The paper describes the modifications made in the half-rate GSM VAD which significantly improve the transmission of information tones, thus enabling the implementation of discontinuous transmission (DTX) in the GSM down-link. The modification consists of the addition of a tone detection algorithm to the basic full-rate GSM VAD architecture. The underlying assumptions behind the tone detector are discussed and the potential performance limitations identified. The half-rate GSM VAD successfully detects almost all tones that are likely to be encountered in networks across the world.
{"title":"Information tone handling in the half-rate GSM voice activity detector","authors":"P. A. Barrett","doi":"10.1109/ICC.1995.525141","DOIUrl":"https://doi.org/10.1109/ICC.1995.525141","url":null,"abstract":"A problem has been identified with the handling of information tones by the full-rate GSM voice activity detector (VAD). The paper describes the modifications made in the half-rate GSM VAD which significantly improve the transmission of information tones, thus enabling the implementation of discontinuous transmission (DTX) in the GSM down-link. The modification consists of the addition of a tone detection algorithm to the basic full-rate GSM VAD architecture. The underlying assumptions behind the tone detector are discussed and the potential performance limitations identified. The half-rate GSM VAD successfully detects almost all tones that are likely to be encountered in networks across the world.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123828658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A method is proposed for forming an adaptive phased array transmission beam pattern at a base station without any knowledge of array geometry, path angles or mobile feedback. Estimates of receive vector channels are used to form a transmit weight vector optimization problem. The authors provide closed form solutions for both the single user case and the multiple user case. They show through simulation of a multiple user cellular network that the cooperative transmission network algorithm is capable of improving network frequency re-use capacity by a factor of 5 to 8.
{"title":"A blind adaptive transmit antenna algorithm for wireless communication","authors":"G. Raleigh, S. Diggavi, V. K. Jones, A. Paulraj","doi":"10.1109/ICC.1995.524451","DOIUrl":"https://doi.org/10.1109/ICC.1995.524451","url":null,"abstract":"A method is proposed for forming an adaptive phased array transmission beam pattern at a base station without any knowledge of array geometry, path angles or mobile feedback. Estimates of receive vector channels are used to form a transmit weight vector optimization problem. The authors provide closed form solutions for both the single user case and the multiple user case. They show through simulation of a multiple user cellular network that the cooperative transmission network algorithm is capable of improving network frequency re-use capacity by a factor of 5 to 8.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121366214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A real-time call admission control algorithm is developed for admitting real time traffic streams with quality of service (QoS) constraints in high-speed networks operating in a packet-switched mode under a fixed routing strategy. The theory developed is based on a calculus for network delay at each network node with general traffic arrival process at the network edge. The authors give the necessary and sufficient conditions for the schedulability of real-time connections at each network node under non-preemptive earliest-due date scheduling policy for deterministic QoS guarantees. These necessary and sufficient conditions form the mathematical basis for the deterministic QoS guarantees in real-time communication services. The manner in which the end-to-end delay bound is to be divided into local delay bounds which together satisfy the end-to-end QoS requirements is finally proposed.
{"title":"A real-time call admission control algorithm in high-speed networks","authors":"Shanzeng Guo, N. Georganas","doi":"10.1109/ICC.1995.525181","DOIUrl":"https://doi.org/10.1109/ICC.1995.525181","url":null,"abstract":"A real-time call admission control algorithm is developed for admitting real time traffic streams with quality of service (QoS) constraints in high-speed networks operating in a packet-switched mode under a fixed routing strategy. The theory developed is based on a calculus for network delay at each network node with general traffic arrival process at the network edge. The authors give the necessary and sufficient conditions for the schedulability of real-time connections at each network node under non-preemptive earliest-due date scheduling policy for deterministic QoS guarantees. These necessary and sufficient conditions form the mathematical basis for the deterministic QoS guarantees in real-time communication services. The manner in which the end-to-end delay bound is to be divided into local delay bounds which together satisfy the end-to-end QoS requirements is finally proposed.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125140684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rainbow is a prototype optical metropolitan area network (MAN) developed at IBM. It employs wavelength division multiplexing (WDM) on a fiber-optic passive-star network topology, with each station equipped with a laser, which is fixed tuned to its own unique wavelength, and a Fabry-Perot filter, which is tunable across all wavelengths. The paper presents a model and analysis of the protocol used in the Rainbow prototype using the equilibrium point analysis (EPA) technique. The authors examine the system's throughput and how it is affected by various system parameters such as message arrival rate, message length, and timeout duration. They show that, for a given arrival rate, there is a timeout duration that will yield the optimal throughput. The analytical results are verified by simulation.
{"title":"Performance analysis of the Rainbow WDM optical network prototype","authors":"J. Jue, M. Borella, B. Mukherjee","doi":"10.1109/ICC.1995.525179","DOIUrl":"https://doi.org/10.1109/ICC.1995.525179","url":null,"abstract":"Rainbow is a prototype optical metropolitan area network (MAN) developed at IBM. It employs wavelength division multiplexing (WDM) on a fiber-optic passive-star network topology, with each station equipped with a laser, which is fixed tuned to its own unique wavelength, and a Fabry-Perot filter, which is tunable across all wavelengths. The paper presents a model and analysis of the protocol used in the Rainbow prototype using the equilibrium point analysis (EPA) technique. The authors examine the system's throughput and how it is affected by various system parameters such as message arrival rate, message length, and timeout duration. They show that, for a given arrival rate, there is a timeout duration that will yield the optimal throughput. The analytical results are verified by simulation.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"26 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113973269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
There are many radio access standards contending for attention in the world-wide cellular marketplace. Practical estimator methods and sequences are introduced for the reference symbol based DS-CDMA radio (denoted "RC"). It is a physical layer scheme involving insertion of a known training sequence into the coded, interleaved bit stream for an IS-95-like CDMA reverse channel. This paper presents the principle estimators needed for implementation of an RC receiver, and frame error rate (FER) results for a flat fading channel. The frame error rate or Eb/No required for a 1% FER is given for both idealized and realistic conditions concerning time varying carrier frequency offset and delay slew of the received timing. A comparison to IS-95 shows a 2 dB improvement.
{"title":"Implementation of a coherent reverse channel 900 MHz CDMA receiver with reference symbols","authors":"T. Sexton, F. Ling","doi":"10.1109/ICC.1995.524256","DOIUrl":"https://doi.org/10.1109/ICC.1995.524256","url":null,"abstract":"There are many radio access standards contending for attention in the world-wide cellular marketplace. Practical estimator methods and sequences are introduced for the reference symbol based DS-CDMA radio (denoted \"RC\"). It is a physical layer scheme involving insertion of a known training sequence into the coded, interleaved bit stream for an IS-95-like CDMA reverse channel. This paper presents the principle estimators needed for implementation of an RC receiver, and frame error rate (FER) results for a flat fading channel. The frame error rate or Eb/No required for a 1% FER is given for both idealized and realistic conditions concerning time varying carrier frequency offset and delay slew of the received timing. A comparison to IS-95 shows a 2 dB improvement.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122874160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Solé-Pareta, D. Sarkar, J. Liebeherr, I. Akyildiz
We address the problem of routing connectionless traffic in an ATM network and propose an adaptive multipath routing scheme that enhances the routing methods employed at the inter-working units (IWUs). We present a scheme that distributes packets among multiple virtual paths (VPs) according to the utilization of the links of these VPs. The utilization of the VPs is determined by a feedback mechanism. We present simulation studies to show the effectiveness of the proposed adaptive multipath routing scheme.
{"title":"Adaptive multipath routing of connectionless traffic in an ATM network","authors":"J. Solé-Pareta, D. Sarkar, J. Liebeherr, I. Akyildiz","doi":"10.1109/ICC.1995.524476","DOIUrl":"https://doi.org/10.1109/ICC.1995.524476","url":null,"abstract":"We address the problem of routing connectionless traffic in an ATM network and propose an adaptive multipath routing scheme that enhances the routing methods employed at the inter-working units (IWUs). We present a scheme that distributes packets among multiple virtual paths (VPs) according to the utilization of the links of these VPs. The utilization of the VPs is determined by a feedback mechanism. We present simulation studies to show the effectiveness of the proposed adaptive multipath routing scheme.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134583730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We study the problem of placing erasure nodes among passive stations in a slotted dual bus network. Erasure nodes are known to improve throughput by allowing slot reuse, it is also known that choices made in locating erasure nodes significantly impact network congestion and overall throughput, especially when traffic patterns are non-uniform. We present algorithms to determine optimal placements of erasure nodes that improve upon prior work on this problem: we present simpler and faster polynomial-time algorithms and also consider various useful cost measures. These algorithms can be used to solve related placement problems in which limits on congestion and existing placements are given as input.
{"title":"Efficient algorithms for erasure node placement on DQDB networks","authors":"B. Narahari, S. Shende, R. Simha","doi":"10.1109/ICC.1995.524239","DOIUrl":"https://doi.org/10.1109/ICC.1995.524239","url":null,"abstract":"We study the problem of placing erasure nodes among passive stations in a slotted dual bus network. Erasure nodes are known to improve throughput by allowing slot reuse, it is also known that choices made in locating erasure nodes significantly impact network congestion and overall throughput, especially when traffic patterns are non-uniform. We present algorithms to determine optimal placements of erasure nodes that improve upon prior work on this problem: we present simpler and faster polynomial-time algorithms and also consider various useful cost measures. These algorithms can be used to solve related placement problems in which limits on congestion and existing placements are given as input.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"401 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122857836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A wavelength-division multiplexing (WDM) based multicasting protocol for a single-hop broadcast-and-select local lightwave network is proposed. The approach employs a control-channel-based media-access protocol that schedules multicast packets while incorporating arbitrary transceiver tuning times and propagation delays. An arbitrary number of data channels (W) supply communication bandwidth to N nodes, where N/spl ges/W. An additional control channel is used for synchronization and scheduling. Each node is equipped with one fixed transmitter and one fixed receiver on the control channel, as well as one tunable (wavelength-agile) transmitter and one or more tunable receivers for data channel access. Results suggest the WDM single-hop multicasting experiences very good performance when multicast size is either small or very large, or when nodes are equipped with multiple receivers.
{"title":"A reservation-based multicasting protocol for WDM local lightwave networks","authors":"M. Borella, B. Muckherjee","doi":"10.1109/ICC.1995.524304","DOIUrl":"https://doi.org/10.1109/ICC.1995.524304","url":null,"abstract":"A wavelength-division multiplexing (WDM) based multicasting protocol for a single-hop broadcast-and-select local lightwave network is proposed. The approach employs a control-channel-based media-access protocol that schedules multicast packets while incorporating arbitrary transceiver tuning times and propagation delays. An arbitrary number of data channels (W) supply communication bandwidth to N nodes, where N/spl ges/W. An additional control channel is used for synchronization and scheduling. Each node is equipped with one fixed transmitter and one fixed receiver on the control channel, as well as one tunable (wavelength-agile) transmitter and one or more tunable receivers for data channel access. Results suggest the WDM single-hop multicasting experiences very good performance when multicast size is either small or very large, or when nodes are equipped with multiple receivers.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"552 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123921451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An improved echo cancellation strategy is presented for telephony networks. The scheme exploits synthetic chaos to code the speech signal resulting in improved performance. The logistic map is utilised as the chaotic encoding mechanism where the bifurcation parameter is directly modulated by the speech signal. This is shown to result in whitening the speech PSD. Utilising the described strategy an echo attenuation of 50.3 dB was achieved after only 2000 iterations (250 ms) as opposed to the conventional 23.4 dB over the same interval. Furthermore, the model misadjustment was -17.8 dB and -82.6 dB after 250 ms of uncoded and chaotic coded speech.
{"title":"Improved echo cancellation over telephony networks exploiting synthetic chaos","authors":"J. Elmirghani, S. Milner, R. Cryan","doi":"10.1109/ICC.1995.525230","DOIUrl":"https://doi.org/10.1109/ICC.1995.525230","url":null,"abstract":"An improved echo cancellation strategy is presented for telephony networks. The scheme exploits synthetic chaos to code the speech signal resulting in improved performance. The logistic map is utilised as the chaotic encoding mechanism where the bifurcation parameter is directly modulated by the speech signal. This is shown to result in whitening the speech PSD. Utilising the described strategy an echo attenuation of 50.3 dB was achieved after only 2000 iterations (250 ms) as opposed to the conventional 23.4 dB over the same interval. Furthermore, the model misadjustment was -17.8 dB and -82.6 dB after 250 ms of uncoded and chaotic coded speech.","PeriodicalId":241383,"journal":{"name":"Proceedings IEEE International Conference on Communications ICC '95","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1995-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124072042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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